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Why flow of current from cathode to anode still the flow of electrons is from cathode to anode?
Anuannz78
The direction of current, according to convention, is the direction opposite the direction of electron flow. Remember that the anode is where oxidation occurs, so electrons are lost by the anode. These electrons then move from the anode, to the cathode by a wire that usually connects the two compartments. To reiterate, the electrons flow from the anode (site of oxidation) to the cathode (site of reduction). Because electrons flow from anode to cathode, by convention the direction of current is from cathode to anode (the direction opposite the flow of electrons). Hope this helps!
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When dissolved in water does sodium nitrate conduct electricity?
In order that a substance can conduct an electric current, the electrical charge has to be able to move through the substance by means of charged particles. In metals, even when they are solid, the metal atoms split into ions and free electrons. These free electrons can move from atom to atom (or, more accurately ion to ion). Therefore, the electrical charge can be carried on these free moving electrons and the metal conducts the electricity. In solid sodium hydoxide, however, there are no free moving charged particles and so solid sodium hydroxide does not conduct. Add water, however, and the sodium hydroxide dissolves to form a solution. In the solution the sodium hydroxide splits into ions - positive sodium ions (Na+) and negative hydroxide ions (OH-) that are free to move about the solution. Therefore the electrical charge can be carried on these free moving particles and so the solution (but not the solid) conducts. If a current is passed through sodium hydroxide solution the Na+ ions are attracted to the negative cathode. Also, Hydrogen ions (H+) from the water are also attracted to the cathode. Because Hydrogen is less reactive than Sodium, it is discharged from the solution (rather than the sodium) so that hydrogen gas is given off. It does this because each Hydrogen ion (H+) can pick up an electron from the current flowing through the cathode to form a hydrogen atom (H). Two atoms will then join up to form a hydrogen molecule H2 which is discharged at the cathode forming hydrogen gas. Similarly in the solution the OH- ions are attracted to the positive anode. Also, Hydroxide ions (OH-) from the water are also attracted to the cathode. Each of the OH- ions deposits an electron to provide the current flowing through the anode. This forms an OH radical which, being unstable, joins with another OH radical formed to produce a water molecule H2O and an oxygen atom. When a pair of oxygen atoms are produced, they join up to form an oxygen molecule O2 which is discharged at the anode forming oxygen gas. Melted Sodium Hydroxide also conducts as the ions are again free to move around in the melted substance. In this case, oxygen is still given off at the anode, but, as there are no hydrogen ions in the liquid because there is no water present, Sodium metal is discharged at the cathode instead.
What are electrons called that inhabit regions of levels the atom?
They are still just called electrons , they don't have a different name.
What type of ion is when an atom loses electrons?
A positive ion. Originally atoms have a neutral charge with equal amount of electrons and protons. If atom loses electrons, it still has the same amount of protons so it becomes a positive ion
What element has more than one shell occupied by electrons but still has the same amount of electrons in each shell?
Beryllium, or Be, has two electrons in both the first and second shell. The atomic number is 4 if you need to find it on the periodic table.
Does Mg 2 contains 15 protons and 10 electrons?
Does Mg 2 contain 15 protons and 10 electrons
What happens when smaller area is provided to cathode than anode?
When the area provided to the cathode is smaller than the anode the electrons will still flow.
What is state of matter forms when a fluorescent light bulb is turned on?
when a fluorescent light bulb is turned on, the state in it is still gaseous state. no change of state occurs by turning it on. It functions like a CRO(search cathode ray oscilloscope). one end acts as a cathode and the other as an anode. electron beam is produced by the cathode and it moves toward the anode. on thier way to anode, electrons collide with the walls of the glass. on the inside of the glass, it is coated with such a material that when electron collides with that surface, it produces a small flash of light. when millions of electrons do that, we see a bulb turned on.
What is a TRIODE and what are its uses?
A triode is a vacuum-tube (US) aka valve(UK) with three electrodes : an anode, a cathode and a grid. The cathode is heated electrically which boils off a cloud of electrons. The anode is made positive ( typ. 100-500V) which attracts the electrons towards it. The grid is an open structure, usually of thin wires, placed between the anode and cathode, but nearer the cathode. If a negative voltage is applied to the grid the current flow through the tube is reduced. The more negative, the less current. Prior to the development of transistors, tubes were used for all things in radio,TV and electronics. Different tubes had different numbers of electrodes; the triode was particularly suited to high power amplifiers, especially at radio frequencies. Triodes are still used today by shortwave radio stations, and for RF heating equipment.
In which direction do electrons flow?
From anode to cathode.
What is seen at the anode when a solution of copper chloride is electrolysed?
In MOLTEN zinc chloride, At the cathode: Zn2+ + 2e- --> Zn(s) At the anode: 2Cl- --> Cl2(g) + 2e- In CONCENTRATED aqueous zinc chloride solution, At the cathode: 2H+ + 2e- --> H2(g) At the anode: 2Cl- --> Cl2(g) + 2e- (Zinc is not formed as it's Enaught value is very negative. Chlorine is still formed though.) In dilute (less than 5%) squeous zinc chloride solution, At the cathode: 2H+ + 2e- --> H2(g) At the anode: 2O2- --> O2(g) + 4e-
Why is it necessary to connect a very high voltage at final anode of a color picture tube?
Electrons striking the phosphors at the front of the picture tube are what generate the photons our eyes see. Electrons (negatively charged) don't move unless forced to by either an electric field or a magnetic field - in this case an electric field - created by the circuitry in the TV. The distance from the back of the picture tube neck where electrons are generated (the cathode, negative charge, repels electrons) to the front of the screen where they are needed is large, perhaps 20 or 30 or more inches. Though the picture tube is evacuated, it is not a perfect vacuum and many atoms still exist inside it, which results in resistance to electron flow. Ohm's Law - Voltage = Current x Resistance - determines what happens electrically. Since the resistance of the atoms inside the tube is quite high to electrons, a high voltage is required to overcome it and force the electrons to move and strike the screen in sufficient quantity (current), after which they fall back to the metal coating inside the picture tube (the anode, positive charge, attracts electrons), completing the circuit that started at the cathode. A lower voltage will simply not provide enough force to do the job.
Why does a plateau exist in the Geiger-Muller region?
In a Geiger-Müller (GM) tube, there is a central anode and a "case" that is the cathode. A voltage is applied across these two elements, and an ionizing particle passing through the GM tube will cause current flow. But how much? Let's step through things and check it out. At low voltage, any electrons released by the cathode will eventually be collected by the anode, but there is no appreciable "current" per se in this, the ionization region. Things are still pretty "tame" in the GM tube through this range of voltages. By applying more voltage, an ionizing event will generate more current flow, and this current flow will be proportional to the voltage in what is (naturally) the proportional region. And as we apply more voltage, gas amplification, or Townsend avalanche, which appeared at the beginning of this region, is increasing across the area of the anode. As we apply even more voltage, it will only make for limited additional current flow in an ionizing event because the limits of the geometry of the GM tube and of the gas media to ionize and "conduct more" with the increasing voltage are being reached. This is the limited-proportional region. As voltage is increased even more, we enter the Geiger-Müller region. In this region, the current avalanche in an ionizing event is so great that is causes a "shield" of positive ions around the anode. The high current "sucks up" all the electrons and blankets the anode in a positive field that prevents additional current flow even with an increase in voltage. This is the Geiger plateau. It's the operating region where additional differential voltage will not cause higher current flow in an ionizing event.
Can you apply forward voltage when anode current fall to zero in scr?
No. Soon after its anode current falls to zero, the device is not is a state to block the forward voltage due to the presence of carriers in its four layers its still in conduction mode. Thus at first it takes some time to remove excess charge from the four layers. Thus just after its anode currents decays to zero it is unable to block the forward voltage.
What are stationary anode x ray tubes?
An x-ray tube where the anode is held still, rather than rotated as would happen in the rotating anode tube.
When dissolved in water does sodium nitrate conduct electricity?
In order that a substance can conduct an electric current, the electrical charge has to be able to move through the substance by means of charged particles. In metals, even when they are solid, the metal atoms split into ions and free electrons. These free electrons can move from atom to atom (or, more accurately ion to ion). Therefore, the electrical charge can be carried on these free moving electrons and the metal conducts the electricity. In solid sodium hydoxide, however, there are no free moving charged particles and so solid sodium hydroxide does not conduct. Add water, however, and the sodium hydroxide dissolves to form a solution. In the solution the sodium hydroxide splits into ions - positive sodium ions (Na+) and negative hydroxide ions (OH-) that are free to move about the solution. Therefore the electrical charge can be carried on these free moving particles and so the solution (but not the solid) conducts. If a current is passed through sodium hydroxide solution the Na+ ions are attracted to the negative cathode. Also, Hydrogen ions (H+) from the water are also attracted to the cathode. Because Hydrogen is less reactive than Sodium, it is discharged from the solution (rather than the sodium) so that hydrogen gas is given off. It does this because each Hydrogen ion (H+) can pick up an electron from the current flowing through the cathode to form a hydrogen atom (H). Two atoms will then join up to form a hydrogen molecule H2 which is discharged at the cathode forming hydrogen gas. Similarly in the solution the OH- ions are attracted to the positive anode. Also, Hydroxide ions (OH-) from the water are also attracted to the cathode. Each of the OH- ions deposits an electron to provide the current flowing through the anode. This forms an OH radical which, being unstable, joins with another OH radical formed to produce a water molecule H2O and an oxygen atom. When a pair of oxygen atoms are produced, they join up to form an oxygen molecule O2 which is discharged at the anode forming oxygen gas. Melted Sodium Hydroxide also conducts as the ions are again free to move around in the melted substance. In this case, oxygen is still given off at the anode, but, as there are no hydrogen ions in the liquid because there is no water present, Sodium metal is discharged at the cathode instead.
What are applications of automatic battery charger using scr?
A Silicon Controlled Rectifier, commonly referred to as a SCR, is a semiconductor that allows current to flow through it only after a momentary positive voltage is applied to the gate. It also converts AC energy to DC energy. AC energy, or alternating current energy, sends the electrons in pulses, not creating a direct flow of electrons around the circuit. DC energy, or direct current energy, sends electrons in a steady flow around the circuit. A Silicon Controlled Rectifier has three leads that include the cathode, the anode, and the gate. Their main purpose is to ensure that electrons are flowing the correct way and to limit the amount of electrons that flow through. Before the gate is "opened", or has been touched by a positive current, the Silicon Controlled Rectifier acts as a wall and does not allow electrons to flow through. In a circuit, when wire leads are connected to the anode and the cathode of the Silicon Controlled Rectifier and an open wire lead has potential to be connected to the gate, it has the ability to stop almost all electrons from passing through or to let electrons pass through by touching the open wire lead to the gate. The three leads of the Silicon Controlled Rectifier play a very important role in how it works. An anode is a lead that the current flows into, and a cathode is a lead where the current flows out of. They send the electrons the correct way around the circuit. They also can stop the flow, or continue the flow, of electrons throughout the circuit. When they are connected, but no positive current has been given to the gate, they act as a break in the circuit that allows little light to get through. When electricity is applied to the gate, the electrons flow through the circuit the correct way and in the positive direction. The gate is what allows the Silicon Controlled Rectifier to turn on and send electricity through it. With a simple, direct touch of electricity, the gate opens and allows the electrons to flow through. The only way to stop the constant flow of electrons after the gate has been touched is to stop the circuit or take out the power source. There is no way to turn off the Silicon Controlled Rectifier after it has already been connected momentarily to a positive current of electrons. The gate is what allows the electrons to move directly throughout the circuit, and it cannot be stopped until the power source is disconnected or it shortens out. One example of a technology that a Silicon Controlled Rectifier is used for is a car alarm. When the car is in the state of being locked, and the window is smashed or the door is opened, it sets the alarm off. When you shut the door, the alarm still goes off, because there is no way to cut the power source without the keys to the car. The robber that broke into the car has no way of stopping the alarm unless he or she finds a way to disconnect the power source to the alarm. This is very useful because the alarm will most likely continue to go off, so the owner of the vehicle can be notified of a potential break in. Another example of a piece of technology that a Silicon Controlled Rectifier is used in is a battery charger. A SCR prevents
What is high power transmitting valves?
A high power transmitting valve is used in a high power transmitter such as a short-wave radio broadcasting transmitter, or a TV transmitter or a radar transmitter etc. High power can mean from less than one kilowatt to hundreds of kilowatts. The 'valve' or 'tube' is a device to amplify electrical signals. Valves were invented at the beginning of the 20th century and were the first way of amplifying an electrical signal. They were the driving force in the development of all aspects of electronic engineering. In the second half of the 20th century transistors and later integrated circuits came to supplant valves. One application of valves that continues to this day is the high power amplification, of radio frequency signals. Although almost all medium wave (broadcast band) and medium power TV transmitters use transistors for amplification, valves are still ised in high power short wave transmitters, some TV transmitters and a special sort of valve is used in microwave transmitters including radar (and also the microwave cooker in a kitchen). In general, a valve comprises a cathode, one or more grids, and an anode all housed in a very high vacuum inside an insulating envelope. The principle of operation is that electrons are forced out of the cathode by heating it with an electrically heated filament rather like the filament in an incandescent lamp. The electron cloud around the cathode is attracted towards the anode by a high voltage connected between the anode (positive) and the cathode (negative). The flow of electrons from cathode to anode can be controlled by an electrostatic field from the grid(s). Thus a change of voltage on the grid will vary the flow of electrons (electric current) flowing from cathode to anode. The valve can be constructed so that a small variation of voltage on the grid can cause a large variation of current between cathode and anode - this is the basis of signal amplification. The electrical efficiency of a valve can be from a few percent up to more than 70% but if it is being used at high power even 70% efficiency will mean that there are high levels (for example 30% of 500 kW) of wasted energy. This wasted energy shows up as heat - so high power transmitting valves typically need some high power cooling systems. Typical cooling systems are air blast cooling from large air blowers and boiling water systems where the heat is used to boil water. It takes a lot of heat to boil a small quantity of water so the water cooling system can be made relatively small. The physical size of valves varies from the size of a pea to as large as a man. High power transmitter valves range in sise from a grapefruit to a beer barrel.
